Oracle SQL語句操作數字：取整、四捨五入、百分化及格式化

用oracle sql對數字進行操作: 取上取整、向下取整、保留N位小數、四捨五入、數字格式化

取整（向下取整）： 
select floor(5.534) from dual;
select trunc(5.534) from dual;
上面兩種用法都可以對數字5.534向下取整，結果爲5.

如果要向上取整 ，得到結果爲6，則應該用ceil
select ceil(5.534) from dual;

 

四捨五入： 
SELECT round(5.534) FROM dual;
SELECT round(5.534,0) FROM dual;
SELECT round(5.534,1) FROM dual;
SELECT round(5.534,2) FROM dual;
結果分別爲 6,  6,  5.5,  5.53

 

保留N位小數（不四捨五入）： 
select trunc(5.534,0) from dual;
select trunc(5.534,1) from dual;
select trunc(5.534,2) from dual;
結果分別是 5,5.5,5.53，其中保留0位小數就相當於直接取整了。

 

數字格式化： 
select to_char(12345.123,'99999999.9999') from dual;
結果爲12345.123

select to_char(12345.123,'99999999.9900') from dual;
小數後第三第四爲不足補0，結果爲12345.1230

select to_char(0.123,'99999999.9900') from dual;
select to_char(0.123,'99999990.9900') from dual;
結果分別爲 .123, 0.123

 

取百分數

select 100*round(COUNT(*)/SUM(COUNT(*)) OVER(),4)||'%' percent FROM  表名